Walid Mohamed Rashad Mohamed | Modern Science and Arts (MSA) university (original) (raw)

Papers by Walid Mohamed Rashad Mohamed

Journal of ecology and the natural environment, Jul 31, 2007

The crested porcupine Hystrix cristata is the biggest rodent in Libya. It has a high value from t... more The crested porcupine Hystrix cristata is the biggest rodent in Libya. It has a high value from the faunistic point. It is known in Libya from only one specimen killed in a suburb of Tripoli in 1962. With aids of an animal dealer in Misurata, this work will provide information on the morphology,feeding habits,habitat, cranial and dental characters of this animal.

Study on regioselective synthesis of bioactive bis‐spiropyrazolines using molecular orbital calcu... more Study on regioselective synthesis of bioactive bis‐spiropyrazolines using molecular orbital calculations

Volume 6B: Energy, 2016

Mini fuel plates used in Advanced Test Reactor (ATR) undergo five steps during the reator operati... more Mini fuel plates used in Advanced Test Reactor (ATR) undergo five steps during the reator operation: startup, ATR Cycle 146A, transition from Cycle 146A to 146B, ATR Cycle 146B, and shutdown. Although the overall irradiation behavior of U-10Mo fuel is expected to be similar to the reactors operating at comparable power levels, there is a concern regarding how variation in operation schedules (that is, how many start-ups and shut-downs could be inserted during the Cycle A and Cycle B) may affect the mechanical behavior of the fuel plate during operation. To investigate any potential effect of number of start-stop activities, we simulated the thermo-mechanical behavior of L1P756 mini-plate, one of fuel plates inserted in ATR under RERTR-12 irradiation conditions with various numbers of start-stop activities artificially added at different points of time in irradiation cycle. This paper reviews four cases by varying the number of thermal cycles. Finite Element (FE) analyses were perfor...

International Journal of Surgery, 2021

Background The COVID-19 pandemic has resulted in significant changes to healthcare systems which ... more Background The COVID-19 pandemic has resulted in significant changes to healthcare systems which impact the delivery of surgical training. This study aimed to investigate the qualitative impact of COVID-19 on surgical training in the United Kingdom (UK) & Republic of Ireland (ROI) Methods This national, collaborative, cross-sectional study involving 13 surgical trainee associations distributed a pan-surgical specialty questionnaire on the impact of COVID-19 on surgical training over 4 weeks in May 2020. Various aspects of training were assessed. Results 810 completed responses were analysed (males=401, females=390) from all deaneries and training grades. The perceived negative overall impact of the pandemic on surgical training experience was significant. (Weighted average = 8.66). 41% of respondents (n=301) were redeployed with 74% redeployed >4 weeks. Complete loss of training was reported in elective operating (69.5%), outpatient activity (67.3%) and endoscopy (69.5%). A reduction of >50% was reported in emergency operating (48%) and completion of work-based assessments (WBAs) (46%). 3.3% (n= 17) of respondents reported plans to leave medicine altogether. Cancellations in study leave and regional teaching programmes without rescheduling were reported in 72% and 60% of the cohort respectively. Elective operative exposure and WBAs completion were the primary reported factors affecting potential trainee progression. Only 9% reported that they would definitely meet all required competencies. Conclusion COVID-19 has had a negative impact on surgical training across all grades and specialties, with implications for trainee progression, recruitment and retention of the surgical workforce. Further investigation of the long-term impact at a national level is required.

International Journal of Cardiology, 2020

International Journal of Clinical Practice, 2021

JES. Journal of Engineering Sciences, 2006

The use of cross frames in bridge is provided to act together with the longitudinal girders to fo... more The use of cross frames in bridge is provided to act together with the longitudinal girders to form a system that behaves as a unit. In horizontally curved bridges, the interaction of bending and torsion causes these components to become major load-carrying elements (primary members) and not secondary members as that in straight girders. This study is concerned with parametric study of the effect of cross frames on the behaviour of composite steel-concrete girders curved in plan using finite element technique. Shoring is assumed to be used during construction and both dead and live loads according to ECP are taken into consideration in the analysis. The concrete deck slab and both steel webs and flanges are modeled using shell elements. However, both studs and cross frames are modeled using beam elements. The study includes not only the displacements but also the tangential stresses through the inner edge, middle and outer edge of the tension flange along the span of the critical outside girder. Based on the numerical results it is shown that slenderness ratio of cross frames, cross frame spacing, radius of curvature, span length and flange width have greatest effect on the warping-to-bending stress ratio. It is shown that equations which can be used for composite girders subjected to noncomposite dead loads and recommended by other authors may give inaccurate results for curved composite systems constructed with shoring. Also, they do not take the slenderness ratio of cross frames into consideration. Two equations are proposed for the preliminary design of cross frame spacing and warping-to-bending stress ratio for curved composite systems constructed with shoring. The accuracy of the results using the new equations is checked for various variables. From equations, it is recommended that the maximum slenderness ratio of cross frames should not exceed 140. Also, the distance between cross frames should be ranged from 3 to 5 m.

Perfusion, 2020

C-reactive protein is a well-known marker of inflammation and may be preoperatively elevated in t... more C-reactive protein is a well-known marker of inflammation and may be preoperatively elevated in the absence of infection in adult cardiac surgery patients, indicating a baseline inflammatory process. We conducted a literature search to assess the available evidence on whether there is an association between preoperative C-reactive protein and acute kidney injury after coronary artery bypass grafting. Included only were observational studies which investigated this association. We excluded abstracts, case reports, animal studies and articles in languages other than English. Altogether, 199 papers were retrieved from the search strategy reported, of which 6 studies were included in the final review. The study types, publication details, patient groups and key results are tabulated. A qualitative assessment of these papers was conducted. We conclude that there is some evidence to support the association between high preoperative C-reactive protein level and postoperative acute kidney i...

Volume 6: Energy, Nov 11, 2019

Monolithic fuel is a candidate fuel form being considered for the conversion of high-performance ... more Monolithic fuel is a candidate fuel form being considered for the conversion of high-performance research reactors. This platetype fuel consists of a high-density, U-Mo fuel in a monolithic form that is sandwiched between zirconium diffusion barriers, and encapsulated in an aluminum cladding. To date, large number of plates have been irradiated with satisfactory performance. The program is now moving into the qualification phase, a predecessor to the timely conversion of the target reactors. Since each reactor employs distinct fuel plate geometries for various consideration, resulting nearly 50 distinct plate geometries with unique plate design features, a single "generic" plate geometry capturing all of the extremities is not achievable. This limitation consequently requires much more cautious performance evaluations, as thermal and mechanical response of a plate with certain geometry may not be representative for a plate with a different geometry. To evaluate the performance of the plates for various geometric parameters, parametric sensitives studies have been employed. One of the important geometric parameters may have potential effects on the performance is the plate curvature. In this study, curvedplates were parametrically simulated to investigate if this geometric parameter has any effects on overall performance, In particular, radius of curvatures of the plates were varied between the bounding values, and the plates were simulated for comparable irradiation histories. The resulted temperature, deformation, stress-strain results were comparatively evaluated. The results have indicated that preferential deformations occur. This consequently caused shifting of plate centerline on curved plates. The magnitude of centerline shifts increased with increasing plate curvatures.

International Journal of Surgery, 2020

Background: Ensuring the highest quality of surgical training remains a challenge as demands on h... more Background: Ensuring the highest quality of surgical training remains a challenge as demands on health service provision rise. This study aimed to explore the differences and potential conflicts between service provision and dedicated training activity provided by surgical trainees, and recommend solutions. Methods: Participants were drawn from the Association of Surgeons in Training (ASiT) national council. Nominal Group Technique (NGT) was employed by members of the ASiT executive addressing 3 key domains (1) defining differences between training and service tasks, (2) impact of service-provision on training and (3) ways to improve training. A two-round Delphi process was conducted via electronic survey to ASiT council. Consensus was considered achieved for any statement where 80% or more of respondents indicated agreement. Results: 47 statements were generated through NGT which were put to the Delphi process. Consensus was reached on a total of 24/47 statements. Educational or training tasks were identified as being activities which progressed a trainee's skill set, could be tailored to a trainee's own ability, and involved acting as a trainer to more junior colleagues. The negative impact of excess service provision included training quality, trainee mental health, and surgical trainee recruitment. Potential measures to improve training included increasing hospital staffing and resources, protected training times, trainee-specific or competency-based learning and training or incentivising trainers. Conclusion: This trainee-based study provides several consensus recommendations on the characteristics that define surgical training and how a balance between service provision and training can potentially be achieved. Policy makers and health systems may be guided by these to ensure high quality training and a satisfied workforce.

Interactive CardioVascular and Thoracic Surgery, 2020

A best evidence topic in cardiac surgery was written according to a structured protocol. The ques... more A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was ‘Is it safe and effective to reduce the target anticoagulation range for patients with mechanical aortic valves?’ Altogether 922 papers were found using the reported search, of which 7 represented the best evidence to answer the clinical question. Only studies that compared high (target international normalized ratio 2–3) versus low (target international normalized ratio <2–3) intensity anticoagulation were included. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. We conclude that there is growing evidence for the reduction of the target anticoagulation range for patients with mechanical prosthetic aortic valves, especially bileaflet valves with presumed better haemodynamic properties. Several large randomized controlled trials and a meta-analysis have concluded th...

Journal of the General Union of Arab Archaeologists, 2018

The Azov museum-reserve (Azov city, the Russian Federation) holds more than 1000 examples (intact... more The Azov museum-reserve (Azov city, the Russian Federation) holds more than 1000 examples (intact ones and fragments) of clay tobacco pipes. All of them are from the excavations carried out on the territory of the former Ottoman fortress Azak (Azov old district) and its surroundings. Until recently, this archeological material has been left unstudied and has not been put into scientific use. The great bulk of finds (over 80%) are Muslim (Turkish) tobacco pipes. These are pipes made by the ceramics craftsmen on the territory of the former Ottoman Empire (Asia Monor, the Crimea, Balkans). They were widely used by the military garrison of the Turkish fortress Azak in private daily life. All in all, Muslim tobacco pipes were discovered by the archeologists in Azov in the cultural layers of XVII-the beginning of XIX centuries. The pipes from four "closed" complexes (three pits and a burial) discovered in 1998-2004 are dated by the end of XVII-the beginning of XVIII centuries according to the coin material. The majority of the tobacco pipes are abundantly ornamented splendid examples of the Muslim ceramics art. Some of them have stamps of their makers and Ottoman inscriptions made in Arabic calligraphy. The variety of pipe "fashions" is highly considerable. A number of the pipes are flower-shaped: as a tulip, a lily, a narcissus,

Authorea

Due to the urbanization and human invasion of the natural environments, a great deal of changes h... more Due to the urbanization and human invasion of the natural environments, a great deal of changes have occurred on the food composition and feeding ecology of several animals especially those are sharing humans their habitats in fields, wadis and gardens. The Desert Hedgehogs Paraechinus aethiopicus populations inhabiting different localities in Saudi Arabia were studied by using stomach contents analysis between February 2015 and October 2019. Precise analysis of 55 stomach contents of hedgehogs showed that the food of The Desert Hedgehogs Paraechinus aethiopicus is highly diverse and highly influenced with effect of humans on the environment includes cooked rice, insects, plant materials, egg shells, worms, garbage and remains of mammals and birds. Diet composition showed seasonal variations that are apparently associated with changes in the availability

International Journal of Economics and Business Administration, 2019

Purpose: The aim of this study is to explore the perceptions of employees working for the Oil Tra... more Purpose: The aim of this study is to explore the perceptions of employees working for the Oil Transportation Department of Libya Oil Company regarding their future outsourcing and their current payment satisfaction. Design/Methodology/Approach : In fact, employees' power has increased dramatically and it cannot be ignored or neglected after the Libyan revolution in February 2011. Despite the fact that outsourcing improves performance, quality, and reduces costs, workers are usually significantly affected within the strategies considered by outsourcing. The literature shows that the employees affected in such outsourcing processes suffer from many problems. The effect of an aggressive culture, such as the Libyan context, on outsourcing employees requires more investigation. One hundred eighty-four workers, from two different operational sites, out of 300, participated in filling in the questionnaire regarding their perceptions of being outsourced to contractors. Findings: The results show that employees perceive outsourcing negatively, and the results indicate that there is a significant relation between the perceived outsourcing impact on individuals and on profession with their payment satisfaction. Practical Implications: Management should consider their employees' perceptions as well before outsourcing. Originality/Value: Executing the strategy of outsourcing employees to contractors seems to be difficult, if not impossible, in an aggressive working environment.

Philosophical Magazine, 2018

Using molecular dynamics simulations and statisticalmechanical metrics, we make quantitative pred... more Using molecular dynamics simulations and statisticalmechanical metrics, we make quantitative predictions on the local thermodynamic and dynamic states following an ion or neutron impact in three materialscopper, silicon and solid argon. Through a two-energy distribution, we first capture the non-equilibrium temperature evolution and the approach to the local thermal equilibrium in three generic stages. By examining the time-resolved van Hove selfcorrelator, we then demonstrate that the impact core of all the three materials shows the dynamic characteristics of a jammed or glassy state. We delineate a dynamic atomhopping mechanism that attests to a rapid defect recovery stage in copper; silicon, on the contrary, accommodates only small displacements which resist recovery. The dissimilitude between copper with a close-packed structure and silicon with an open network structure is further drawn out through an isoconfigurational analysis of displacements, which shows a compact dendritic-like condensation front for the mobile atoms in copper through atom hopping. In contrast, silicon portrays larger-scale spatial oscillations of dynamically separated regions, which appear to be a precursor to dynamic lattice instability and eventual amorphisation.

Materials Science and Engineering: A, 2018

This study is focused on furthering our understanding of the different factors that influence the... more This study is focused on furthering our understanding of the different factors that influence the formability of Magnesium alloys. Towards this end, formability studies were undertaken on a wrought Mg-2Zn-1Mn (ZM21) alloy. In contrast to conventional formability studies, the impression testing method was adopted here to evaluate the formability parameter, B, at temperatures ranging from 298 to 473 K. The variation of B of ZM21 with temperature and its rather limited values were discussed in the light of different deformation mechanisms such as activation of twinning, <c+a> slip, grain boundary sliding (GBS) and dynamic recrystallization (DRX). It was found that the material characteristics such as grain size, texture and testing conditions such as temperature and strain rate, were key determinants of the mechanism of plastic deformation. A by-product of this analysis was the observation of an interesting correlation between the Zener-Hollomon parameter, Z, and the ability of Mg alloys to undergo DRX.

International journal of medical microbiology : IJMM, 2018

Staphylococcus aureus can cause wide range of infections from simple soft skin infections to seve... more Staphylococcus aureus can cause wide range of infections from simple soft skin infections to severe endocarditis, bacteremia, osteomyelitis and implant associated bone infections (IABI). The focus of the present investigation was to study virulence properties of S. aureus isolates from acute and chronic IABI by means of their in vivo lethality, in vitro osteoblasts invasion, biofilm formation and subsequently whole genome comparison between high and low virulent strains. Application of insect infection model Galleria mellonella revealed high, intermediate and low virulence phenotypes of these clinical isolates, which showed good correlation with osteoblast invasion and biofilm formation assays. Comparative genomics of selected high (EDCC 5458) and low (EDCC 5464) virulent strains enabled the identification of molecular factors responsible for the development of acute and chronic IABI. Accordingly, the low virulent strain EDCC 5464 harbored point mutations resulting in frame shift mu...

Journal of Nuclear Materials, 2017

In this study, smaller-grained (hundred nano-meter size grain) and larger-grained (micro-meter si... more In this study, smaller-grained (hundred nano-meter size grain) and larger-grained (micro-meter size grain) U-10Mo specimens have been irradiated (implanted) with 250 keV Xe + beam and were in situ characterized by TEM. Xe bubbles were not seen in the specimen after an implantation fluence of 2×10 20 ions/m 2 at room temperature. Nucleation of Xe bubbles happened during heating of the specimen to a final temperature of 300 ˚C. By comparing measured Xe bubble statistics, the nucleation and growth behaviors of Xe bubbles were investigated in smaller-grained and larger-grained U-10Mo specimens. A multi-atom kind of nucleation mechanism has been observed in both specimens. X-ray Absorption spectroscopy showed the edge position in the bubbles to be the same as that of Xe gas. The size of Xe bubbles has been shown to be bigger in larger-grained specimens than in smaller-grained specimens at the same implantation conditions.

BMC Microbiology, 2016

Background: Staphylococcus aureus is the principle causative pathogen of osteomyelitis and implan... more Background: Staphylococcus aureus is the principle causative pathogen of osteomyelitis and implant-associated bone infections. It is able to invade and to proliferate inside osteoblasts thus avoiding antibiotic therapy and the host immune system. Therefore, development of alternative approaches to stimulate host innate immune responses could be beneficial in prophylaxis against S. aureus infection. TLR9 is the intracellular receptor which recognizes unmethylated bacterial CpG-DNA and activates immune cells. Synthetic CpG-motifs containing oligodeoxynucleotide (CpG-ODNs) mimics the stimulatory effect of bacterial DNA. Results: Osteoblast-like SAOS-2 cells were pretreated with CpG-ODN type-A 2216, type-B 2006, or negative CpG-ODN 2243 (negative control) 4 h before infection with S. aureus isolate EDCC 5055 (=DSM 28763). Intracellular bacteria were streaked on BHI plates 4 h and 20 h after infection. ODN2216 as well as ODN2006 but not ODN2243 were able to significantly inhibit the intracellular bacterial growth because about 31 % as well as 43 % of intracellular S. aureus could survive the pretreatment of SAOS-2 cells with ODN2216 or ODN2006 respectively 4 h and 20 h post-infection. RT-PCR analysis of cDNAs from SAOS-2 cells showed that pretreatment with ODN2216 or ODN2006 stimulated the expression of TLR9. Pretreatment of SAOS-2 cells with ODN2216 or ODN2006 but not ODN2243 managed to induce reactive oxygen species (ROS) production inside osteoblasts as measured by flow cytometry analysis. Moreover, treating SAOS-2 cells with the antioxidant Diphenyleneiodonium (DPI) obviously reduced S. aureus killing ability of TLR9 agonists mediated by oxidative stress. Conclusions: In this work we demonstrated for the first time that CPG-ODNs have inhibitory effects on S. aureus survival inside SAOS-2 osteoblast-like cell line. This effect was attributed to stimulation of TLR9 and subsequent induction of oxidative stress. Pretreatment of infected SAOS-2 cells with ROS inhibitors resulted in the abolishment of the CPG-ODNs killing effects.